Difference between revisions of "If Command"
From GeoGebra Manual
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; If[ <Condition>, <Then> ] | ; If[ <Condition>, <Then> ] | ||
: Yields a copy of the object ''Then'' if the condition evaluates to ''true'', and an undefined object if it evaluates to ''false''. | : Yields a copy of the object ''Then'' if the condition evaluates to ''true'', and an undefined object if it evaluates to ''false''. | ||
− | :{{ | + | :{{Examples|1=<div> |
+ | :*Let ''n'' = 3. <code><nowiki>If[n==3, x + y = 4]</nowiki></code> yields line ''x'' + ''y'' = 4, because the condition on number ''n'' is met. | ||
+ | :*Let ''n'' = 4. <code><nowiki>If[n==3, x + y = 4]</nowiki></code> creates an ''undefined'' object, because the condition on number ''n'' is not met .</div>}} | ||
; If[ <Condition>, <Then>, <Else> ] | ; If[ <Condition>, <Then>, <Else> ] | ||
− | : Yields a copy of object ''Then'' if the condition evaluates to ''true'', and a copy of object ''Else'' if it evaluates to ''false''. | + | : Yields a copy of object ''Then'' if the condition evaluates to ''true'', and a copy of object ''Else'' if it evaluates to ''false''. Both objects ''must'' be of the same type. |
− | + | :{{example|1= Let ''n'' be a number. <code><nowiki>If[n==3, x + y = 4, x - y = 4]</nowiki></code> yields line ''x'' + ''y'' = 4 when ''n'' = 3, and line ''x'' - ''y'' = 4 for all ''n'' not equal to 3.}} | |
− | :{{example|1= | ||
− | |||
− | |||
===Conditional Functions=== | ===Conditional Functions=== | ||
− | :The | + | :The ''If'' command can be used to create conditional functions. Such conditional functions may be used as arguments in any command that takes a function argument, such as [[Derivative Command|Derivative]], [[Integral Command|Integral]], and [[Intersect Command|Intersect]]. |
:{{Examples|1=<div> | :{{Examples|1=<div> | ||
:* <code>f(x) = If[x < 3, sin(x), x^2]</code> yields a piecewise function that equals ''sin(x)'' for ''x < 3'' and ''x<sup>2</sup>'' for ''x ≥ 3''. | :* <code>f(x) = If[x < 3, sin(x), x^2]</code> yields a piecewise function that equals ''sin(x)'' for ''x < 3'' and ''x<sup>2</sup>'' for ''x ≥ 3''. | ||
:* <code>f(x) = If[0 <= x <= 3, sin(x)]</code> yields a function that equals ''sin(x)'' for x between 0 and 3 (and undefined otherwise).</div>}} | :* <code>f(x) = If[0 <= x <= 3, sin(x)]</code> yields a function that equals ''sin(x)'' for x between 0 and 3 (and undefined otherwise).</div>}} | ||
− | :{{ | + | :{{notes|1=<div> |
− | + | :* Derivative of ''If[condition, f(x), g(x)]'' gives ''If[condition, f'(x), g'(x)]''. It does not do any evaluation of limits at the critical points. | |
+ | :* See section: [[Boolean values]] for the symbols used in conditional statements.</div>}} | ||
==If Command in Scripting== | ==If Command in Scripting== | ||
− | : | + | :''If'' command can be used in scripts to perform different actions under certain conditions. |
− | :{{example|1= Let ''n'' be a number, and ''A'' a point. The command <code>If[Mod[n, 7] == 0, SetCoords[A, n, 0], SetCoords[A, n, 1]]</code> modifies the coordinates of point ''A'' according to the given condition. In this case it would be easier to use <code> SetCoords[A, n, If[Mod[n, 7] == 0,0,1]]</code>. | + | :{{example|1= Let ''n'' be a number, and ''A'' a point. The command <code>If[Mod[n, 7] == 0, SetCoords[A, n, 0], SetCoords[A, n, 1]]</code> modifies the coordinates of point ''A'' according to the given condition. In this case it would be easier to use <code> SetCoords[A, n, If[Mod[n, 7] == 0,0,1]]</code>.}} |
− | }} | + | :{{note|1= Arguments of ''If'' must be Objects or [[Scripting Commands]], not assignments. Syntax <code><nowiki>b = If[a > 1, 2, 3]</nowiki></code> is correct, but ''b = 2'' or ''b = 3'' would not be accepted as parameters of If.}} |
− | :{{note|1= Arguments of |
Revision as of 10:04, 2 August 2013
- If[ <Condition>, <Then> ]
- Yields a copy of the object Then if the condition evaluates to true, and an undefined object if it evaluates to false.
- Examples:
- Let n = 3.
If[n==3, x + y = 4]
yields line x + y = 4, because the condition on number n is met. - Let n = 4.
If[n==3, x + y = 4]
creates an undefined object, because the condition on number n is not met .
- Let n = 3.
- If[ <Condition>, <Then>, <Else> ]
- Yields a copy of object Then if the condition evaluates to true, and a copy of object Else if it evaluates to false. Both objects must be of the same type.
- Example: Let n be a number.
If[n==3, x + y = 4, x - y = 4]
yields line x + y = 4 when n = 3, and line x - y = 4 for all n not equal to 3.
Conditional Functions
- The If command can be used to create conditional functions. Such conditional functions may be used as arguments in any command that takes a function argument, such as Derivative, Integral, and Intersect.
- Examples:
f(x) = If[x < 3, sin(x), x^2]
yields a piecewise function that equals sin(x) for x < 3 and x2 for x ≥ 3.f(x) = If[0 <= x <= 3, sin(x)]
yields a function that equals sin(x) for x between 0 and 3 (and undefined otherwise).
- Notes:
- Derivative of If[condition, f(x), g(x)] gives If[condition, f'(x), g'(x)]. It does not do any evaluation of limits at the critical points.
- See section: Boolean values for the symbols used in conditional statements.
If Command in Scripting
- If command can be used in scripts to perform different actions under certain conditions.
- Example: Let n be a number, and A a point. The command
If[Mod[n, 7] == 0, SetCoords[A, n, 0], SetCoords[A, n, 1]]
modifies the coordinates of point A according to the given condition. In this case it would be easier to useSetCoords[A, n, If[Mod[n, 7] == 0,0,1]]
.
- Note: Arguments of If must be Objects or Scripting Commands, not assignments. Syntax
b = If[a > 1, 2, 3]
is correct, but b = 2 or b = 3 would not be accepted as parameters of If.